Color developers using aromatic primary amine color developing agents have long been used in color image-forming processes and, at present, they play a central role in color photographic image-forming processes. As is well known, however, the above-described color developers are quite susceptible to oxidation by air or metals. When color images are formed using an oxidized developer, increased fog or a change in sensitivity or gradation results, thus adversely affecting desirable photographic properties.
Therefore, various techniques have been developed for improving the preservability of a color developer, and a process using hydroxylamine and sulfite ion in combination is most popularly employed. However, when decomposed, hydroxylamine produces ammonia which causes fog, and sulfite ion functions as a competing compound with respect to a developing agent to inhibit color formation, and neither is a preferred preservative.
In addition, various preservatives and chelating agents have conventionally been used for improving stability of color developer. For example, such preservatives include aromatic polyhydroxy compounds described in Japanese Patent Application (OPI) Nos. 49828/77, 160142/84, 47038/81 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), U.S. Pat. Nos. 3,746,544, etc.; hydroxycarbonyl compounds described in U.S. Pat. No. 3,615,503 and British Pat. No. 306,176; .alpha.-aminocarbonyl compounds described in Japanese Patent Application (OPI) Nos. 143020/77 and 89425/78; alkanolamines described in Japanese Patent Application (OPI) No. 3532/79; metal salts described in Japanese Patent Application (OPI) Nos. 44148/82 and 53749/82, etc. Chelating agents include aminopolycarboxylic acids described in Japanese Patent Publication Nos. 30496/73 and 30232/69; organophosphonic acids described in Japanese Patent Application (OPI) No. 97347/81, Japanese Patent Publication No. 39359/81, and West German Patent No. 2,227,639; phosphonocarboxylic acid compounds described in Japanese Patent Application (OPI) Nos. 102726/77, 42730/78, 121127/79, 126141/80, 65956/80, etc.; and compounds described in Japanese Patent Application (OPI) Nos. 195845/83 and 203440/83, Japanese Patent Publication No. 40900/78, etc.
However, these techniques still fail to provide sufficient preservability, or adversely affect photographic properties, remaining unsatisfactory.
In particular, color developers which do not contain benzyl alcohol, which is harmful in view of environmental pollution and preparation of the developers, necessarily lose color-forming ability and, in such systems, the preservatives functioning as competing compounds so seriously inhibit color formation that many conventional techniques are found to be unsatisfactory.
Further, Japanese Patent Application (OPI) Nos. 95345/83 and 232342/84 disclose that color photographic materials containing a chloride-rich silver chlorobromide emulsion are liable to form fog upon color development. When using such emulsions, preservatives having a reduced solubility for silver halide emulsions and better preservability are necessary. However, satisfactory preservatives have not been found.